[F] Fix RuntimeError: Timeout context manager should be used inside a task

https://github.com/dashezup/github-webhook-to-telegram/issues/3

main.py

@@ -43,24 +43,15 @@ async def github_webhook_post_handler(request: Request) -> Response:
     tg_chat_id: Union[str, int, bool] = await validate_github_webhook(request)
     if not tg_chat_id:
         return web.Response(status=403, text="403: Forbidden")
-    tg_status = await send_to_telegram(session, tg_chat_id, request)
+    async with ClientSession() as session:
+        tg_status = await send_to_telegram(session, tg_chat_id, request)
     return web.Response(text=f"Send to Telegram: {tg_status}")
 
 
-async def get_session() -> ClientSession:
-    return ClientSession()
-
-
-async def on_shutdown(_):
-    await session.close()
-
-
 if __name__ == "__main__":
     # FORMAT = "[%(filename)s:%(lineno)s - %(funcName)20s() ] %(message)s"
     # logging.basicConfig(level=logging.INFO, format=FORMAT)
-    session: ClientSession \
-        = asyncio.get_event_loop().run_until_complete(get_session())
     app = web.Application()
     app.add_routes(routes)
-    app.on_shutdown.append(on_shutdown)
     web.run_app(app, port=PORT)
+